How to identify Clustered Brittlestem

To correctly identify Clustered Brittlestem (Psathyrella piluliformis), check each of these features in order. Misidentification is the most common cause of mushroom poisoning, so cross-reference multiple sources.

Step-by-step identification

1. 1

   Cap

   Shape, color, surface texture, and diameter.

   The cap is 2-7 cm in diameter, initially convex to campanulate, expanding to broadly convex or plano-convex, often with a low umbo. The margin is initially incurved, becoming straight, and often striate when moist. The color ranges from reddish-brown to tawny or cinnamon-brown when moist, fading to buff, tan, or yellowish-brown when dry (hygrophanous). The surface is smooth, sometimes finely pruinose when young, and often has veil remnants along the margin when immature.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   The gills are adnate to adnexed, close to crowded, and narrow. They are initially whitish to pale grayish, becoming purplish-brown to dark brown with age due to spore maturation. There are numerous lamellulae (short gills).

3. 3

   Stem

   Length, shape, surface, and any ring.

   The stem is 3-10 cm long and 0.3-1 cm thick, central, cylindrical, often slightly tapering upwards, and hollow. It is whitish to pale brownish, often pruinose at the apex, and can be finely fibrillose below. It is brittle and lacks a persistent ring, though a faint, evanescent fibrillose zone may be present from the partial veil.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   The flesh is thin, fragile, whitish to pale brownish, and lacks a distinctive odor or taste.

5. 5

   Fruiting body

   Overall growth pattern.

   The fruiting body is typically gregarious to densely caespitose (clustered), emerging from decaying wood.

6. 6

   Habitat

   Where it grows and on what substrate.

   Saprobic, growing in dense clusters on decaying hardwood logs, stumps, and buried wood. Occasionally found on conifer wood. It is a common decomposer in deciduous and mixed forests.

Key Facts

Cap surfaces

Smooth, sometimes finely pruinose, hygrophanous

Growth Form

Caespitose (clustered)

Spore Print

Dark purplish-brown

Body color

Reddish-brown to tawny (moist), buff to tan (dry)

Odor

Indistinct

Flesh bruises

Does not bruise

Height

3-10 cm

Cap Diameter

2-7 cm

Fruit body characteristics

• Gill attachment: Adnate to adnexed
• Stem shape: Cylindrical, often slightly tapering upwards
• Stem surface: Whitish to pale brownish, often pruinose at apex, finely fibrillose below
• Ring: Absent or an evanescent fibrillose zone
• Stem cross-section: Hollow

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